Abstract: A flat-plate camera for X-ray diffraction studies of powdered materials under various conditions of temperature. A spindle assembly is provided for rotating a sample specimen about the longitudinal axis of the sample and such that the axis of an X-ray beam striking the specimen, orthogonally intersects the longitudinal axis of the specimen. The spindle assembly includes means for providing a temperature controlled air stream which is directed towards the sample specimen along its longitudinal axis for varying the sample temperature. A flat film plate to be exposed is vertically mounted in back of the sample specimen and is asymmetrically arranged with respect to the X-ray beam. An X-ray shield is provided to permit exposure of sequential segments of the film plate thereby providing direct comparison on one photograph of different exposures taken at various sample temperatures.